Glycogen Synthase Kinase-3 as a drug target for Trypanosoma brucei African sleeping sickness is a parasitic disease afflicting up to 500,000 persons in Africa, often with fatal outcomes. New therapeutics are needed for African sleeping sickness, caused by Trypanosoma brucei spp. Glycogen synthase kinase-3 is a critical kinase enzyme found in many eukaryotic organisms. In preliminary data, we have shown that: 1) inhibition of T. brucei GSK-3 expression leads to in vitro cell growth arrest;and 2) inhibitors of GSK-3 lead to growth arrest and cell death of T. brucei and their activity against cells correlates with their activity against GSK-3 enzyme. Though GSK-3 inhibitors kill T. brucei, specific GSK-3 inhibitors do not appear toxic to mammals even with chronic administration. Thus, GSK-3 is an excellent target for developing drugs to treat T. brucei infections. The overall purpose of this application is to better understand T. brucei GSK-3 and use this information to develop lead compounds that target GSK-3 for the treatment of African sleeping sickness. The Aims of this project include: 1) Further develop small molecule GSK-3 inhibitors as potential drugs for African sleeping sickness ("hit to lead" development);newly synthesized compounds will be tested for specific activity against T. brucei GSK-3 and cells vs, mammalian kinases and cells to improve potency and specificity;2) Use modeling of the T. brucei GSK-3 structure or solve the T. brucei GSK-3 structure and use structure-based-drug development to direct synthesis of compounds in SA #1 to help improve potency of the compounds;and 3) further validate the target by modifying GSK-3 enzyme in T. brucei parasites to be inhibited by specialized molecules that will only inhibit modified GSK-3 enzyme. Having inhibitors that only inhibit T. brucei GSK-3 is key to understanding the biological and pharmacological effects of GSK-3 inhibition on T. brucei parasites. At the end of this project, we will have critical information about GSK-3 inhibitors for the therapy of African sleeping sickness and will have developed 2 to 3 lead compounds to take forward for optimization as potential therapeutics. PUBLIC HEALTH RELEVANCE: Glycogen Synthase Kinase-3 as a drug target for Trypanosoma brucei this project is to investigate Glycogen Synthase Kinase-3 as a possible drug target for T. brucei and to develop new drugs based on the leads we have found. T. brucei infection, causing African Sleeping Sickness, is of public health significance because it is estimated to cause between 300,000 and 500,000 infections per year in Africa, most of which end fatally. The available drugs for T. brucei infection are very toxic, some of them causing up to 5% mortality from the therapy alone. New drugs for this infection are clearly needed.